Magnetic subharmonic pulser



PI' 14 1959 Kuo-CHEN Hu 2,882,426

MAGNETIC SUBHARMONIC PULSER med nec. 27, 1955 l mi?. 6,@ A f rf IN VEN TOR. l 0g-WIEN H6 to t tz Y 4 6 7 t "BY M 'United States Patent MAGNETIC SUBHARMONIC PULSER Kuo-Chen Hu, Levittown, Pa.

Application December 27, 1955, Serial No. 555,338

14 Claims. (Cl. 307-106) My invention relates to a magnetic subharmonic pulser which will deliver a pulse from an alternating current power source once in an integral number of cycles. More specifically, the device of my novel invention will deliver pulses of any subharmonic of the alternating supply voltage frequency. By way of example, if a sixty cycle power supply is used, pulses of the frequency of thirty cycles per second which is a second subharmonic, twenty cycles per second which is a third subharmonic, fteen cycles per second which is a fourth subharmonic, and so on, could be obtained.

Many applications utilize subharmonic generators of the type to which my novel invention is directed. For example, in computers, a device of this type is desirable for switching purposes or triggering where the input frequency is at a much higher frequency than the sixty cycles given in the above example. Another application of this type of device may be found in a low frequency standard wherein an accurate low frequency signal is obtained by using a subharmonic frequency of a tuning fork which has an extremely accurately calibrated high frequency output. Still further applications may be found in subharmonic ringing as used in telephone devices, and a still further application may be found in the blinking of a traic light for warning or other similar purposes. It is therefore seen that a subharmonic generating device .would have universal applications too numerous to mention here.

subharmonic generators are well known in the art and are usually based on the principal of a saturable reactor having a D.-C. bias or in utilizing the property of subharmonic oscillation in a circuit containing a capacitor and a non-linear inductance, generally known as ferroresonance.

In the case of circuits utilizing a D.C. biased transductor, it has been found that only the even order of subharmonics can be produced and these usually being only of the second order or one-half of the supply frequency.

In the case of devices using subharmonic oscillation due to the connection of a capacitor and nonlinear inductance, it has been found that their operation is determined by the property of the core material. Hence, once the core material is fixed, little can be done to change the order of subharmonics which are generated by varying other parameters such as the capacitor and the number of turns on the saturable reactor.

The principal of my invention is to provide a subharmonic generator which utilizes a reactor which may have a core of saturable type material wherein saturation of the magnetic material of the core is effective to allow an output pulse to be transferred from an A.C."line to a load and to thereafter drive and maintain the magnetic core in an unsaturated condition for a predetermined number of cycles of the A.C. power line. As will be shown hereinafter in the utilization of my novel invention, the core material becomes merely a design parameter rather' than a dominating factor in the subharmonics which can be transferred to the load. Similarly by easy adjustment of circuit components, it will be shown that the subharmonic order produced may be easily adjusted.

As will be described more fully hereinafter, the preferred embodiment of my invention comprises a circuit including a capacitor, a reactor which may have a core of saturable type material, a lirst and second winding on said reactor, a resistor and a rectifier. An output load is then connected in series with an A.C. power source, and the above mentioned capacitor, the first and second winding of the reactor and a rectifier. Hence, as the potential of the A.C. source becomes positive, it will eventually saturate the magnetic core of the reactor and a charging current will flow through the capacitor in series with the load to deliver a pulse thereto. As the potential of the A.-C. source reverses, its potential will fall across the series connected rectifier in the blocking direction and the charged capacitor is then allowed to discharge through the resistor and into the abovementioned first winding to thereby begin to reset the ilux of the saturable reactor or to drive the ilux of the saturable reactor in its unsaturated direction.

During the next half cycle, in the event that the capacitor has not completely discharged, both the voltage source and the charge remaining in the capacitor will be effective to drive the flux of the saturable reactor in opposite directions. That is to say the voltage of the input A.-C. source will attempt to drive the reactor to saturation whereas the residual charge in the capacitor will attempt to defeat this saturation. Hence, during the half cycle in question it is seen that if the capacitor has sufficient residual charge, that the reactor will be maintained in its unsaturated state. This process is then continued for as many cycles as is required to have the voltage source completely overcome the capacitor residual charge to thereby drive the reactor to saturation and subsequently recharge the capacitor and simultaneously impart a second pulse to the load.

Hence, by controlling the charge and discharge of the capacitor by adjusting the resistor, the capacitor itself or the configuration of the magnetic core windings, the number of cycles of the A.C. source per pulse may be easily controlled.

Accordingly, the primary object of my invention is to provide a magnetic subharmonic pulser for delivering an output pulse once in a predetermined number of cycles of an A.-C. power source.

Another object of my invention is to provide a magnetic subharmonic pulser for providing subharmonic pulses from an A.C. power source wherein a capacitor and saturable reactor are utilized in coordination with the voltage of the power source to maintain the reactor unsaturated for a predetermined number of cycles.

Another object of my invention is to provide a magnetic subharmonic pulser which includes a gate circuit and a reset circuit wherein the gate circuit is effective to drive the magnetic ux of a saturable reactor toward a saturation condition whereby a pulse is delivered to a load, and the reset circuit is effective to drive the magnetic iiux of the saturable reactor in a direction to oppose saturation thereof, this reset circuit being further constructed to oppose saturation of the magnetic core for a predetermined integral number of cycles to the A.-C. source.

Another object of my invention is to provide a magnetic subharmonic pulser which `comprises a saturable reactor and a capacitor wherein the capacitor is charged in series with the saturable reactor to thereby deliver a pulse from an A.-C. source to a load and the charge on the capacitor is thereafter effective to drive and maintain the saturable reactor in an unsaturated state for a predetermined number of cycles of the A.C. source.

These and "other objects of my invention will become evident upon consideration of the description in conjunction with the ligures wherein Figure l is a circuit diagram of one embodiment of my novel invention.

Figure 2 shows the flux-ampere turns characteristic ofthe saturable reactor of Figure 1.

Figure 3 shOws the current-time characteristic of the circuit 'of Figure l. y

Figure '4 shows a modification of the circuit of Figure 1.

Referring now to Figure l', it is seen a voltage source 'is connected to energize a load 11 with 'a pulse once in every predetermined number of cycles of the A.C. source 10. The source Y10 is more sp'ecilic'ally connected in series with the capacitor 12,- a rst winding or vreset winding 13 of the transductorshown generally at 14, a second winding or a gate Winding 15 'of the transductor 14, a rectifyi'ng means 16 and the load 11. The resistor 17 whichm'ay, if desired, be an adjustable resistor is then connected to complete a reset circuit comprising the closed series connection of the capacitor 12, winding 13 and resistor 17 and a gate circuit which comprises the series connection of the A-.C.{ source 10, resistor 17, winding 15, rectier 16 'and the load 11.

It is yto be noted that the saturable reactor shown generally at 14 is comprised of the reset winding 13, the gate winding 15 and a magnetic core Which is schematically shown as the core 18. This magneticcore may, if desired, be of a highly saturable type material so that the magnetizing current of the windings 13 and is is srnan with respect to the pulse current through the load 11.

The operation of the circuit of Figure 1 may now be taken in conjunction with the diagrams of Figures 2 and 3. Each of Figures 2 and 3 are related to a common time axis and show the typical operation of the circuit of Figure l when adjustments of the components are such that a fourth subharmonic pulse is transferred from the A.C. source 10 to the load 11. y

lt is lirst assumed that a steady state is reached and Vthat the core saturates somewhere between the times to and t1 of Figure 3. Since the voltage em is positive 'at the time of saturation which is shown as time 'tf in Figure l3, it is seen that the capacitor 12 will carry a charging current from the A.C. source 1t? which is in a direction to be passed by the rectiiier 16. Since the saturable reactor 14 is assumed to have saturated at this time, is realized that the impedance of the windings '13A'and 15 is negligible.

lIt is to be further 'realized that the time tf at which saturation of the core 13 of the saturable reactor 14 takes place depends on the ux level of the core at to of Figure -3 which is shown as rpo in Figure 2. Hence, the following relation holds:

c tf CTload tf is impressed across the reset winding 13 in such a direction as to demagnetize the core 18 to drive the flux of the core toits unsaturated condition. This condition may be seen in Figure 2 as the flux change Ar'plnz in which the discharge current of the capacitor 12 is limited to the magnetizing current of the saturable reactor 14 4 plus the current that would be drawn by the reected impedance of the gate circuit.

A study of the circuit of Figure 1 indicates that during the interval p1 to e2 which is in question the induced voltage in the winding 15 which is due to the capacitor discharging into the winding 13 is in the same direction as iL which is the load current during the previous period and thus encounters very little forward resistance due to the rectifier 16. It should however be noted that the reversed polarity of the A.C. supply 10 'will'oppose this flow of current. This is extremely important in the embodiment of Figure 1 for if any current ows due t0 the induced voltage in winding 15 it will be reflected back to the reset circuit and the capacitor will discharge quickly without changing the ilux level of the core 13 in any appreciable manner. The rectier 16 is necessarily provided in the circuit in order to prevent a reversal of load current when the supply voltage exceeds the induced voltage in winding 15 due 'to the discharge of the capacitor 12.

However, reversing current which would be present in the absence of the rectifier 16 would act to reset the linx as does the capacitor 12 and may be, in some applications, used to certain advantage.

-D'uring the neXt interval t2 to t3 seen in Figure 3, the voltage of the A.C. voltage supply It) will now tend to drive the core back to a saturated condition while the remnant voltage or residual charge left on the vcapacitor will tend to demagnetize it further thereby opposing the effect of the supply voltage. The het y'change of linx iis `therefore given by:

in which Ng represents the number of yturns lof the gate circuit winding 15, Ns is the number of turns on the reset winding 13 and V12 is the instantaneous voltage appearing across the capacitor 12.

This net change of llux A 2. 3 may be seen in Figure 2 as being in an opposite direction to the initial flux change Aq 1 2. In this case the magne'tizing current for the core 18 of the saturable rector -14 'is supplied by the 4source 10 and the induced voltage in the reset circuit will drive a current in a direction to discharge the capacitor 12. It is, however, essential to note that the discharge current of the capacitor 12 ows through the series connected variable resistor 17. Hence, the overall discharge of the capacitor 12 may be directly controlled by adjustment of the resistor 17 However, the ladjustment of the discharge of capacitor 12 may be equally determined by the number of turns of windings 13, 15, or if desired, by the size of the capacitor itself.

This point is of great significance since it is this 'feature of my novel circuit that determines exactly how many cycles are required to saturate `the core 18 of the saturable reactor 14 after passage of a pulse t'o Hthe load 11. That is 'to say, it is 'the 'determining factor of the order of the subharmonic which will 'be supplied Vbly the power source 10.

It may now be understood that the above described sequence Vor events is repeated until the core l18 of Figure 1 is finally saturated again at the exact same instant tf. Hence in the interval t3 tot.; of Figure 3, Vit isseen that the flux change A`b3 4 takes place, and in the interval f4 to t5 of Figure 3 that the flux change A4 5 takes place. Similarly, flux changes which correspond to the intervals t5 to te, t6 to t7, and t7 to t0 takeplace as identitled in Figure 2 as A5 6, A5 q and `A 7 0 vUpon the next half cycle, the flux change Aeonf takes place upon which time another pulse is carried to "the load 11.

Therefore, .by adjusting'the circuit components of v*Figure 1 to give the operation defined in Figures A2 `and i3, it is seen that an output pulse will be obtained forevery four cycles of the alternating power source 1l). .It is obvious that by adjusting this cycling operation that any integral number of cycles could produce one pulse.

It has been found that in order to produce a relatively high order of subharmonic output that an auxiliary resetting circuit is desirable as is shown in Figure 4. Figure 4 is similar to Figure 1 but shows an auxiliary reset circuit energized from the source which cornprises the auxiliary rectifier 19 and auxiliary adjustable resistor 20 which are connected to energize the auxiliary reset winding 21 of the saturable reactor core 18. In view of the description of the operation of Figure l, it is now obvious that the auxiliary reset winding 21 will, if the rectifier 19 is connected in the proper direction, supplement the operation of the capacitor 12 in resetting the iiux of the core 18 of saturable reactor 14. More specifically, if the resistor 20 is of a very high value in relation to the resistor 17, it is realized that the auxiliary reset winding 21 will operate as a Vernier type of winding to permit extremely accurate adjustment of the output subharmonic. That is to say, it will provide an extremely accurate adjustment of the number of cycles required to drive the core 18 to saturation.

In the foregoing, I have described my invention solely in connection with specific embodiments thereof. Since many variations and modifications of my invention will now be obvious to those skilled in the art, I prefer to be bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said magnetic subharmonic pulser comprising a magnetic core, a gate circuit and a reset circuit; said magnetic core having a reset winding and a gate winding wound thereon; said gate circuit including the series connection of said A.C. source, said load and said gate winding; said reset circuit including the series connection of a voltage derived from said A.C. source and said reset winding; said gate circuit being constructed to drive the magnetic flux of said magnetic core toward saturation; said reset circuit being constructed to drive the magnetic ux of said magnetic core in a direction to oppose saturation; the magnetomotive force generated by said reset circuit being directed to oppose saturation of said magnetic core for a predetermined integral number of cycles after said gate circuit saturates said magnetic core to thereby deliver a pulse to said load.

2. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said magnetic subharmonic pulser comprising a magnetic core, a gate circuit and a reset circuit; said magnetic core having a reset winding and a gate Winding wound thereon; said gate circuit including the series connection of said A.C. source, said load and said gate Winding; a capacitor; said reset circuit including the series connection of a voltage derived from said A.C. source, said capacitor and said reset winding; said gate circuit being constructed to drive the magnetic flux of said magnetic core toward saturation; said reset circuit being constructed to drive the magnetic flux of said magnetic core in a direction to oppose saturation; the magnetomotive forcegenerated by said reset circuit being directed to oppose saturation of said magnetic core for a predetermined integral number of cycles after said gate circuit saturates said magnetic core to thereby deliver a pulse to said load.

3. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said magnetic subharmonic pulser comprising a magnetic core, a gate circuit and a reset circuit; said magnetic core having a reset winding and a gate winding wound thereon; a rectier, said gate circuit including the series connection of said A.C. source, said load, said rectifier and said gate winding; a capacitor, said reset circuit including the series connection of a voltage derived from said A.C. source, said capacitor and said reset winding; said gate circuit being constructed to drive the magnetic fiux of said magnetic core toward saturation; said reset circuit being constructed to drive the magnetic flux of said magnetic core in a direction to oppose saturation; the magnetomotive force generated by said reset circuit being directed to oppose saturation of said magnetic core for a predetermined integral number of cycles after said gate circuit saturates said magnetic core to thereby deliver a pulse to said load.

4. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an AfC. source of power; said magnetic subharmonic pulser comprising a magnetic core, a gate circuit and a reset circuit; said magnetic core having a reset winding and a gate winding wound thereon; said gate circuit including the series connection of said A.C. source, said load and said gate winding; a capacitor; said reset circuit including the series connection of a voltage derived from said A.C. source, said capacitor and said reset winding; said gate circuit being constructed to drive the magnetic ux of said magnetic core toward saturation; the magnetomotive force generated by said reset circuit being directed to drive the magnetic flux of said magnetic core in a direction to oppose saturation; said reset circuit, said A.C. source and said gate circuit being further constructed to charge said capacitor in series with said load when said magnetic core is saturated.

5. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said magnetic subharmonic pulser comprising a magnetic core, a gate circuit and a reset circuit; said magnetic core having a reset winding and a gate winding wound thereon; a rectifier, said gate circuit including the series connection of said A.C. source, said load, said rectifier and said gate winding; a capacitor, said reset circuit including the series connection of a voltage derived from said A.C. source, said capacitor and said reset winding; said gate circuit being constructed to drive the magnetic ux of said magnetic core toward saturation; the magnetomotive force generated by said reset circuit being directed to drive the magnetic ux of said magnetic core in a direction to oppose saturation; said reset circuit, said A.C. source and said gate circuit being further constructed to charge said capacitor in series with said rectifier and said load when said magnetic core is saturated; the charge on said capacitor to thereafter be operative to reverse the ux of said magnetic core in opposition to said A.C. source whereby said magnetic core is saturated once in every predetermined integral number of cycles.

6. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series; said resistor being connected to complete a closed series connection of said capacitor, said first winding and said resistor; said resistor further completing aclosed series connection including said A.C. source, said load, said rectifier, said second winding and said resistor.

7. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said subharmonic pulser comprising a magnetic core having a iirst and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series, said resistor being connected to complete a closed series connection of said capacitor, said first winding and said resistor; said capacitor being charged responsive to saturation of said magnetic core, said charge on said capacitor thereafter being clective `to drive and maintain said magnetic core in an unsaturated state for a predetermined number of cycles.

8. A magnetic -subharmonic pulser for delivering subharmonic pulses toa l'oad from an A.C. source of power; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series, said resistor being connected to complete a closed series connection of said capacitor, said first winding and said resistor; said capacitor being charged responsive to saturation of said magnetic core, said charge on said capacitor thereafter being effective to drive and maintain said magnetic core in an unsaturated state for a predetermined number of cycles, at least one of said lfirst and second winding, said resistor and said capacitor being adjustable whereby the number of cycles at which said magnetic core is unsaturated is selectively maintained.

9. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series, said resistor being connected to vcomplete a closed series connection of said capacitor, said first winding and said resistor; said capacitor being charged responsive to saturation of said magnetic core, said charge on said capacitor thereafter being effective to drive and maintain Asaid magnetic core in an unsaturated state for a predetermined number of cycles, ysaid resistor being adjustable for selectively maintaining said predetermined number of cycles at which said magnetic core is unsaturated.

10. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power.; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series; said resistorbeing connected to complete a closed series connection of said capacitor, said first winding and said resistor; said capacitor being charged responsive to saturation of said magnetic core; the charging current of said vcapacitor being carried by said load connected in series with said capacitor.

y 11. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from .an A.C. source of power; said sub'harmonic pulser comprising a magnetic core having a first and second Winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, `said rectifier and said load being connected in series; said resistor being connected to complete .a closed series connection of said capacitor, said first winding and said resistor; said capacitor being charged responsive to saturation of said magnetic core; the charging current of said capacitor being carried by said load connected in series with said capacitor; said charged capacitor being discharged in coordination With the alternating voltage of said A.C. source to effect cycling of the fiux of said magnetic core for a lpredetermined number of cycles .prior to resaturat-ion of said magnetic core.

12. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said subharmonic pulser comprising a magnetic core hav- .ing a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first andsecond windings, said rectifier and said load being connected in series; said resistorbeing `connected to 'compl'ete 1a closed series connectionl of said capacitor, said first winding and said resistor; anauxiliary circuit and an auxiliary winding; said auxiliary winding being wound on said magnetic core; said auxiliary circuit being energized from said A.C. source and constructed to energize said auxiliary winding to -drive the flux `of said magnetic core inthe same direction as said' rst winding when said first Winding is energized by the discharge of said capacitor.

13. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from an A.C. source of power; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said first and second windings, said rectifier and said load being connected in series; said resistor being connected to complete a closed series connection of said capacitor, .said first winding and said resistor; ,an auxiliary circuit and an auxiliary winding; said auxiliary winding being wound in said magnetic core; said auxiliary circuit comprising an auxiliary rectifier and an :auxiliary resistor being energized from said A.C. source and constructed to energize said auxiliary winding to drive the fiux of said magnetic core in the same direction as said rst winding When said first winding is energized by the discharge of said capacitor.

14. A magnetic subharmonic pulser for delivering subharmonic pulses to a load from 4an A.C. source of power; said subharmonic pulser comprising a magnetic core having a first and second winding, a capacitor, a resistor and a rectifier; said A.C. source, said capacitor, said -first and second windings, said rectified and said load being connected in series; said resistor being 'connected to complete a closed series connection of said capacitor, said first winding and said resistor; said capa-citer being charged responsive to saturation of said magnetic core; Ythe charging current of said capacitor being carried by said load connectedV in series with said capacitor; said charged capacitor being discharged in coordination with the alternating voltage of said A.C. source to effect cycling of the ux of said magnetic core for a predetermined number of cycles prior to resaturation of said magnetic core; an auxiliary circuit and an auxiliary winding; said auxiliary winding being wound on said magnetic core; said auxiliary circuit being energized from said vA.C. source and constructed to energize said auxiliary winding to drive the flux of said magnetic core in the sam'e direction as said first winding when said first winding is energized by the discharge of said capacitor.

References Cited in the file of this patent UNITED STATES PATENTS 

